I have seen a lot of interest in waterfalls and dramatic cliffs on these boards, and figured I should post my world generation recipe that favors these features. I have also added a large section to the waterfall article on the wiki about finding natural waterfalls with ease: rather than repost all the images here, I will simply link to it.
http://df.magmawiki.com/index.php/Waterfall#Locating_a_natural_waterfallUsing this recipe, I just found a nice 3x3 location with sand and coal, centered around a 39-level waterfall from a stream plummeting into a major river filled with hippos and fish that will never kill my framerate by freezing during the winter. In the past I have found areas with up to three waterfalls of varying heights. The best waterfalls are found in areas where two rivers meet or where one river becomes a larger one (ie minor ->major), and this recipe creates a patchwork world where rivers are free to tangle. It takes slightly longer to gen than most.
This first spoiler is the recipe.
[WORLD_GEN]
[TITLE:GRANDEUR]
[DIM:129:129]
[EMBARK_POINTS:1274]
[END_YEAR:500]
[BEAST_END_YEAR:200:80]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:80001:80001]
[RAINFALL:0:100:4000:4000]
[TEMPERATURE:60:75:2000:2000]
[DRAINAGE:0:100:4000:4000]
[VOLCANISM:0:100:4000:4000]
[SAVAGERY:0:100:8000:8000]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:0:0:1:1:1:5]
[DRAINAGE_FREQUENCY:0:0:1:1:1:10]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:1]
[VOLCANISM_FREQUENCY:1:1:1:1:1:5]
[TITAN_NUMBER:5]
[TITAN_ATTACK_TRIGGER:80:0:100000]
[DEMON_NUMBER:15]
[GOOD_SQ_COUNTS:24:244:0]
[EVIL_SQ_COUNTS:24:244:0]
[PEAK_NUMBER_MIN:200]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:100]
[REGION_COUNTS:SWAMP:0:0:0]
[REGION_COUNTS:DESERT:0:0:0]
[REGION_COUNTS:FOREST:0:0:0]
[REGION_COUNTS:MOUNTAINS:0:0:0]
[REGION_COUNTS:OCEAN:0:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:0:0:0]
[REGION_COUNTS:HILLS:0:0:0]
[EROSION_CYCLE_COUNT:250]
[RIVER_MINS:800:600]
[PERIODICALLY_ERODE_EXTREMES:0]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:90000]
[CAVERN_LAYER_COUNT:3]
[CAVERN_LAYER_OPENNESS_MIN:100]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:10]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:10]
[CAVERN_LAYER_WATER_MIN:50]
[CAVERN_LAYER_WATER_MAX:50]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:15]
[LEVELS_ABOVE_LAYER_1:5]
[LEVELS_ABOVE_LAYER_2:2]
[LEVELS_ABOVE_LAYER_3:2]
[LEVELS_ABOVE_LAYER_4:2]
[LEVELS_ABOVE_LAYER_5:2]
[LEVELS_AT_BOTTOM:1]
[CAVE_MIN_SIZE:5]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:25]
[NON_MOUNTAIN_CAVE_MIN:50]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:40]
[TOTAL_CIV_POPULATION:20000]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:0:0:0]
[RAIN_RANGES:0:0:0]
[DRAINAGE_RANGES:0:0:0]
[SAVAGERY_RANGES:0:0:0]
[VOLCANISM_RANGES:0:0:0]
This second spoiler details the changes I made to the recipe, and why. You may wish to make changes to my recipe, and this should help you decide where.
Lowered end year to 500: Because I was tired of races dying out. You may wish to stop gen sooner, all humans had died by year 500 on the map I just genned with the 39-level waterfall. I'm going to regen with all the same seeds and stop generation at 200.
An extra zero in the variance levels for elevation etc: Because I like a more patchwork world, with lots of tiny biomes.
Relative frequency adjustments: high rain, high drainage (eliminated aquifers), and high volcanism, because I like forests and obsidian layers/volcanoes and dislike aquifers.
Added many more starting peaks: to give the many rivers somewhere to start that resists erosion.
Added starting volcanoes: because I like building forts in dramatic landscapes, and what is more dramatic than a volcano?
Region counts all set to 0:0:0: This lowers rejects substantially, and lets the relative frequencies work without interruption. I do this for all custom recipes.
Erosion cycle count unchanged: theoretically, I could add to this for wider rivers and fewer mountains, but it's well balanced as is.
River Count increased to 800:600: 800 is the number of minimum rivers pre-erosion. 600 is the number of rivers that must exist post erosion. The many peaks provide excellent starting locations for rivers.
Periodically erode extremes set to 0 (no): This keeps landscapes properly jagged and leaves the possibility of massive cliffs.
Subregion Max set to 90,000: This goes along with the high variance mentioned earlier. A high subregion max prevents the map from being rejected due to having too many biomes. The editor inside DF only goes up to 20,000, but I haven't found an upper limit when editing the world_gen file directly.
CAVERN STUFF: Openness to 100, because I wanted to see what it did (I still don't know), Density to 10 because I don't like highly dense labyrinths but do like the occasional spire, and water to 50 to guarantee nice pools and 'rivers' underground.
Fewer layers between cave systems: Because the layers above the lower river don't contain caverns, and a thirty story waterfall will create all the layers of soil and rock you will ever need. Everything below that is extra.
Boosted civ number: because I like lots of civs, and this lowers the chances of all of a given race dying off.
Elevation etc. ranges all set to 0:0:0 : Like doing the same to region counts, this lowers rejects substantially, and lets the relative frequencies work without interruption. I do this for all custom recipes.